This invention is related to the shock compaction preprocessing of high Tc superconducting starting materials which are to be fabricated into various superconducting constructs.
The novel physical properties of high-temperature superconducting materials create substantial challenges for their use in practice applications. In particular, the low magnetic flux pinning energies found in high-temperature superconductors severely limit the critical current densities of these materials (Khurana, Phys. Today, p. 17, 1989). For example, the pinning energy, U.sub.o, of superconducting fluxoids is a few hundredths of an eV at finite temperatures. This energy is small compared to about 1 eV fluxoid pinning energy for conventional superconductors. The combination of small flux-pinning energies and the persistence of superconductivity to higher critical temperatures, (T.sub.c), causes large flux-creep rates and melting of the Abrikosov flux lattice at a temperature T.sub.m &lt;T.sub.c.
It is a possibility that weak flux pinning is observed by broad resistive transitions in a magnetic field (Tinkham, Phys. Rev. Lett., Vol. 61, p. 1658, 1988) and small intrinsic or intragranular critical current densities J.sub.c. For YBa.sub.2 Cu.sub.3 O.sub.7-e, for example, T.sub.c =90.degree. K., T.sub.m .perspectiveto.80.degree. K., and U.sub.o =0.02 eV at 70.degree. K. (Gammel, et al., Phys. Rev. Lett., Vol. 61, p. 1666, 1988; Roas et al., Appl. Phys. Lett., Vol. 54, p. 1051, 1989) The need to increase U.sub.o and J.sub.c is especially great at 77 K in order to facilitate economically feasible applications of high-T.sub.c materials with liquid nitrogen as a coolant.
Another characteristic of the new high T.sub.c superconductors is that they often require relatively high temperature sintering processing for a variety of reasons. It would be very advantageous to be able to modify the temperature required for effective sintering of these materials.